1. Field of the Invention
This invention generally relates to a developer wringing and removing apparatus. More particularly, the invention relates to a developer wringing and removing apparatus in a liquid developing transfer type electrophotographic copying machine which can eliminate fog by wringing excess developing solution stuck to the surface of a photosensitive member and by removing toner stuck to an undeveloped portion of the photosensitive member and floated in a layer of developer, after an electrostatic latent image on the photosensitive member has been liquid-developed.
2. Description of the Prior Art
In a liquid developing transfer type electrophotographic copying machine, developer is brought into direct contact with a photosensitive member for development so that upon completion of development a large amount of developer sticks to the surface of a photosensitive member. Therefore, toner also sticks to undeveloped portions of a photosensitive member and floats also in a layer of developer. Then, a high voltage corona discharger is employed to impart a corona discharge by means of its high current so as to be able to wring excess developer without disturbing a developed image and to remove toner adhering to the undeveloped portions and floating toner. However, recent requirement of high speed copying by a copying machine causes a moving speed of a photosensitive member (a rotational speed in case of a photosensitive drum) to extremely be speeded up. When this moving speed of a photosensitive member is high, excess developer may not sufficiently be removed only by the aforesaid high voltage corona discharger. This will require a higher voltage corona discharger. However, if it is too high, spark discharge or the like occurs in the corona discharger itself and between the corona discharger and the photosensitive member thus producing such disadvantages as to make pin-holes in the photosensitive member. A further disadvantage is such that when the corona discharging voltage is dropped, wringing effect of developer is reduced and drying in a drying process after transferring a developed image to a transfer material becomes insufficient, thus requiring a large capacity of a dryer. For these reasons, developer can not completely be wrung only by means of a corona discharger.